Bill,
I'm not sure this will apply to '67 or not, but mine ('66) had a couple of medium green stripes on the frame bracket that I discovered after some EvapoRust soaking. I also see that it was applied to a restored example on Virginia Mustang's blog, '66 GT350 Carryover car, restored by Jeremy at Maple Hill. His shows just a single stripe and the washer looks like P & O, but can't be certain. Others hopefully will weigh in. It's an opportunity for me to learn something new again, if nothing else.